<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #d1{
            width: 100px;
            height: 100px;
            border: 1px solid red;
           /* margin-top: 100px;
            margin-left: 50px;
            margin-bottom: 50px;*/
            /*四个方向*/
            /*margin: 50px;*/
            /*     上下    左右*/
            /*margin: 50px 100px;*/
            /*居中写法*/
            /*margin: 0 auto;*/
            /*上右下左  顺时针赋值*/
            margin: 10px 20px 30px 40px;
        }
        #d2{
            width: 100px;
            height: 100px;
            border: 1px solid blue;
            /*上下相邻彼此添加外边距，去最大值*/
            /*margin-top: 20px;*/
            margin-top: 50px;
        }

        /*行内元素上下外边距无效*/
        #s1{margin-right: 50px}
        /*左右相邻彼此添加外边距，两者相加*/
        #s2{margin-left: 50px}
        #big{
            width: 200px;
            height: 200px;
            background-color: green;
        }
        #big>div{
            width: 50px;
            height: 50px;
            background-color: purple;
            margin-left: 50px;
            margin-top: 50px;
        }
    </style>
</head>
<body>
    <span id="s1">span1</span>
    <span id="s2">span2</span>
    <div id="d1"></div>
    <div id="d2"></div>
</body>
</html>